Various bistatic intrusion detectors exist for detecting the intrusion of persons or equipment across a line; e.g. a border or area perimeter. Exemplary detectors are discussed in the following U.S. Pat. Nos.: 2,203,807, 3,237,105, 3,618,083, 3,618,091, 3,696,368, 3,877,002, 4,605,922, 4,697,184. A bistatic detector is comprised of a microwave transmitter and receiver, which, when deployed, are typically spaced from one another by several hundred feet. Processor means monitors the microwave energy received by the receiver and interprets a signal variation greater than a certain threshold as constituting an intrusion or alarm condition.